Recently, the IEEE (Institute of Electrical and Electronic Engineers) 1394 high speed serial bus has been popularized. A plurality of nodes (for example, such as a digital AV (audio visual) equipment can be connected to the IEEE (Institute of Electrical and Electronic Engineers) 1394 high speed serial bus (hereinafter merely referred to as IEEE1394 bus), and information can be delivered and received between the nodes. Out of nodes connected to the IEEE1394, the node for controlling other nodes is called a controller, and the node controlled by the controller is called a target.
In the transmission standard of IEEE1394, a signal format and an AV/C command for controlling equipment are provided. However, in the transmission standard of IEEE1394 alone, for example, where two pieces of digital AV equipment are connected one to one, no problem occurs, but where three pieces or more are connected one another, there gives rise to a problem. For example, where there is simultaneous control of three nodes or more, and there is a plurality of nodes (controllers) for controlling other equipment (target), there gives rise to a problem that it is difficult or realize to offer mediation between the control nodes (controllers) and to attain development of application softwares in which compatibility is present between nodes.
On the other hand, recently, for the purpose of making the most of characteristics of IEEE1394 capable of actually providing data transmission speed at a high speed and at relatively low cost and capable of solving the problem, the technique called HAVi (Home Audio/Video interoperability) has ben developed.
The HAVi will be described briefly hereinafter.
With the recent conspicuous growth of digital AV equipment market, it is expected that the time will come in future when users can connect the equipment to construct a network in individual home. Accordingly, in order that the equipment on the home network cooperate and operate, each equipment need be provided with a middle ware for control and management of the network. Further, even where equipment of different makers are connected, in order that the network normally operates and the equipment can be used mutually, a common specification to which the middle ware should conform is indispensable thereto.
The HAVi is contemplated as a specification for AV equipment corresponding to the home network making use of IEEE1394. The software in conformity to the HAVi functions as a middle ware arranged between an application and OS (Vendor Specific Platform) in collecting functions used in common for an application as shown in FIG. 21, and in digital AV equipment in conformity to the HAVi on which the former is mounted, mutual use between equipment and mutual utilization of function become enabled. The HAVi has characteristics having a plug and play, mutual operability of equipment, and expandability of a network. Accordingly, when equipment in conformity to HAVi is connected to a network, the software in conformity to HAVi immediately detects the connection of equipment automatically due to the pug and play function, whereby the procedure as the network is taken to realize the expandability with respect to the function of equipment connected.
That is, in the HAVi, a user merely connects various equipment, due to the plug and play function, by a digital interface such as IEEE1394 to enable construction of a home network. Accordingly, even where for example, new equipment is connected to or removed from the network, the equipment can communicate each other to recognize that the network be updated, so that the network can correspond to an arrangement of new equipment without stopping the function.
Further, in the equipment based on the HAVi specification, not only mutual connection and mutual operation between equipment but also co-owning of function between equipment on the network become enabled due to the mutual operability of equipment. For example, by operating certain equipment, it is possible to make use of function of other equipment not possessed by the former.
Furthermore, in the HAVi, the expansion of function is possible such that a new function used in a future new home network application is used on the home network already used by a user, due to the expandability of the network. That is, the specification of HAVi defines the function that usable application programs and user interface softwares in other equipment are incorporated into the own through the network to use them, enhancing the way of pleasure and the convenience of new AV equipment as home network equipment, and having the expandability corresponding to the function to be effective in future. Accordingly, where new equipment or function is developed, that equipment is merely connected to the network already constructed to enable operation thereof.
As described above, the HAVi is possible to detect or control equipment in conformity to HAVi despite the difference in equipment makers, and further, the HAVi application is possible to control individual devices in different equipment. For example, as equipment such as a digital VTR and an audiophile, there can be listed a tuner, a display, an Amp, a stream converter, a clock function, an internet access function, and a modem. According to HAVi, for example, these devices can be operated directly from an application such as a set top box (STB).
The HAVi specification is determined in order to correspond to various requests of the home network in the digital AV environment based on the IEEE1394, and the basic specification thereof defines the exchange of messages and events on the IEEE1394, the ability detection of devices over the whole network and registration, and softwares for management of a digital AV stream and control of devices. As a byte code of the HAVi, Java (Trademark) is employed in order to realize the devices on the network and functions thereof, without depending on a platform, and a bidirectional application and a user interface can be provided. The application in conformity to HAVi based on the Java is loaded on the device to enable download through the modem and the internet. Further, in the HAVi, a resource manager is loaded to process a conflict of the using right of devices, manage a scheduled event such as reserved telerecordings of digital VTR, and monitor a network whether or not a device is removed after registration.
Main software elements defined in the HAVi basic specification include, as shown in FIG. 21, CMM (IEEE1394 Communication Media Manager), EM (Event Manager), Registry, MS (Messaging System), DCM (Device Control Module), DCM manager, DDI controller (Data Driven Interaction Controller), SMGR (Stream Manager), and Resource Manager.
The CMM functions as an interface between the IEEE1394 and each software element.
The EM informs other software elements about the status change of the network (for example, equipment is newly connected to or disconnected from the network).
The MS functions as an API (Application Programming Interface) in which software elements of equipment on the network communicate each other. It is noted that API is an interface positioned between an application and OS or a middle ware.
The DCM control equipment. An application program controls equipment through the DCM. For this reason, the application program itself need not consider the difference between the individual equipment.
The DCM manager updates DCM. When new equipment is additionally connected to the network, DCM necessary for the equipment is newly added to automatically correspond to updating of the network.
The registry controls and store information about the software module.
The DDI controller takes charge of GUI (Graphical User Interface) of a display bock of equipment. This corresponds to a variety of displays from a display of a text alone to a display of graphics.
The SMGR monitors and manages a flow of stream data of IEEE1394 such as a picture and a voice or sound on the network.
The resource manager manages the resource of the network.
The HAVi classifies the device on the network into four categories, i.e. FAV (Full AV Device), IAV (Intermediate AV Device), BAV (Base AV Device), and LAV (Legacy AV Device).
That is, as shown in FIG. 22, the FAV is a device provided with all software elements (all elements marked by check marks in the figure) of HAVi; the IAV is a device provided with software elements (elements marked by check marks in the figure) other than the executing environment of the byte code of Java; the BAV is a device for supporting only HAVi SDD (HAVi Self Describing Device) data and DCM; and LAV is a device other than IEEE1394 not corresponding to HAVi or IEEE1394. It is noted that in the figure, softwares in which a check mark is surrounded by [ ] are option, indicating that the software element may not be provided as the case may be.
FIG. 23 shows one constitutional example of a case where these four categories of devices are connected to a IEEE1394 bus. In the FIG. 23 example, FAV an IAV enable control by DCM with respect to BAV and LAV.
Incidentally, there is contemplated a case where a target corresponding to LAV mentioned in HAVi capable of delivering and receiving an AV/C command of IEEE1394, a controller corresponding to LAV mentioned in HAVi capable of delivering and receiving an AV/C command of IEEE1394, and a controller corresponding to FAV and LAV mentioned in HAVi are present in the same network.
For example, where the controller corresponding to the LAV and the controller in conformity to the HAVi simultaneously control a single LAV on the network as a target, the LAV as the target is to be controlled by a plurality of controllers to possibly give rise to inconvenience.
For example, as shown in FIG. 24, where STB (Set Top Box) 202 which is LAV mentioned in HAVi, STB 201 which is FAV mentioned in HAVi, and digital VTR (for example, such as digital VHS) 203 which is LAV mentioned in HAVi are such that in the network connected by the IEEE1394 bus, both the STB 202 and STB 202 operate as a controller, and the digital VTR 203 is a target, when these two STB 201 and 202 attempt to carry out operation of the digital VTR 203 simultaneously, confliction occurs. That is, since STB 202 operated as a controller is LAV, it is not put under an obligation to have a resource manager, and since LAV is not a model in conformity to HAVi, it is not put under an obligation to carry out communication between controllers, thus giving rise to confliction. For example, where in the midst of telerecording by the digital VTR 203 by the control from one STB 201, a stop command is supplied from the other STB 202, the digital VTR 203 becomes stopped despite the telerecording is in the midst.
Accordingly, where a plurality of controllers capable of controlling a single target are present on the network, and a controller which is LAV not in conformity to HAVi is present in the controllers, there occurs inconvenience that the single target is controlled by the plurality of controllers unless some resource managements are carried out.
Also in the case of network as shown, for example, in FIGS. 25 to 27, in addition to the FIG. 24 example, confliction occurs.
That is, where a controller 208 which is FAV having FCM for LAV corresponding to a reserve command, a controller 207 which is FAV, and a target 209 which is LAV not corresponding to a reserve command are a network connected by IEEE1394 bus, as shown in the example of FIG. 25, since the target 209 is LAV and does not correspond to the reserve command, even if the controller should have a resource manager, resource management could not be done. Accordingly, when these two controllers 207 and 208 attempt to carry out operation of the target 209, confliction similar to that mentioned above occurs.
Where a controller 214 having FCM for BAV not corresponding to a reserve command, a controller 213 which is FAV, and a target 215 which is BAV not corresponding to a reserve command are a network connected by IEEE1394 bus, as shown in the example of FIG. 26, since the target 215 is BAV of a model in conformity to HAVi but does not correspond to the reserve command, even if the controller should have a resource manager, resource management could not be done. Accordingly, even if all the networks should be constructed by the model in conformity to HAVi, when these two controllers 213 and 214 attempt to carry out operation of the target 209, confliction similar to that mentioned above occurs.
Further, where in a network in which a controller 217 which is LAV without resource manager, a controller 2161 which is likewise IAV without resource manager, and a target 218 which is LAV or BAV (BAV having own DCM, FCM) are connected by IEEE1394 bus, as shown in the example of FIG. 27, the controllers make reservations at a target, since both the controllers 216 and 217 are LAV and have not source manager, the resource management cannot be done. Accordingly, when these two controllers 216 and 217 attempt to carry out operation of the target 218, confliction similar to that mentioned above occurs.
Where a control object device which is a target is under the control of single equipment which is a controller, all control request from other control equipment are eliminated whereby confliction of control between control equipment can be avoided. However, by the mere response of the elimination to the control requests, the aforementioned other control equipment cannot distinguish whether the state that the control equipment occupies the control object device or the state that the control object device cannot be controlled for separate reasons. For example, where the digital VTR 203 in the FIG. 24 example receives a control request of reproduction in a power-off state, it repeats a response representative of rejection despite control is not occupied by anybody. Accordingly, the control equipment is necessary to know the state of the control object device in further detail.
Further, in the case of a network constructed by merely by LAV on which a resource manager is not actually mounted, since the respective LAV has no resource manager representative of the occupied state of a control object device, it is not possible to know whether or not certain control equipment obtains possessory rights to control the control object device.
Moreover, in the case of a network system having no equipment in conformity to HAVi, since a function representative of the occupied state of the control object device is not present, the respective control equipment cannot know easily the occupied state of control of the control object device.